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September Weather in Denver, United States

Last updated: June 24, 2025

In September, the average temperature in Denver, United States hovers around 23°C (74°F), with minimums dipping to 8°C (46°F) and maximums soaring to 35°C (95°F). Expect about 128 mm (5.0 in) of precipitation spread over 9 days, while the air stays comfortably humid at an average of 75%.

September Temperature in Denver

In September in Denver, the average temperature is 23°C (74°F). Maximums can reach 35°C (95°F), while minimums can drop as low as 8°C (46°F). This makes Denver an ideal destination for travelers seeking a pleasant and varied climate.

September Weather in Denver: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Denver, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Denver, September typically has an average temperature of 23°C (74°F), with highs reaching up to 35°C (95°F) and lows dropping to around 8°C (46°F).
JanFebMarAprMayJunJulAugSepOctNovDec434853617076817874645046
Data source: Temperature data for Denver generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in Denver

In Denver in September, the precipitation amount is 128 mm (5.0 in) over a span of 9 days.

September Precipitation Trends in Denver

The chart displays monthly precipitation patterns in Denver, with values for each month alongside September’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how September’s conditions compare to those of other months. In Denver, September typically receives around 128 mm (5.0 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec9011687111119798810312810787119
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Denver

In Denver in September, humidity is 75%. With an average temperature of 23°C (74°F), this humidity feels like a warm, heavy blanket wrapping around you, making it feel more sweltering than it actually is, which can be quite uncomfortable for traveling.

September Average Humidity in Denver

This chart illustrates the average monthly humidity levels in Denver, with September’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In September, average humidity in Denver is approximately 75%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec86%85%84%82%83%82%80%74%75%79%87%87%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Denver

In Denver in September, the maximum UV index is 9, which corresponds to a very high Exposure Category. The time to burn is just 15 minutes, so it's essential to take precautions. For detailed information, you can check the Hourly UV Index in Denver.

Maximum UV Index Levels in Denver for September

The chart shows the monthly maximum UV Index (UVI) for Denver in September, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In September, the maximum UV index in Denver typically reaches 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec46810101111109853
Data source: Denver September UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

How September Weather in Denver Compares to Other Months

Weather in Denver varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Denver, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in Denver, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather6°C (43°F)90 mm (3.5 inches)86%moderate
February Weather9°C (48°F)116 mm (4.6 inches)85%high
March Weather12°C (53°F)87 mm (3.4 inches)84%very high
April Weather16°C (62°F)111 mm (4.4 inches)82%very high
May Weather21°C (70°F)119 mm (4.7 inches)83%very high
June Weather25°C (77°F)79 mm (3.1 inches)82%extreme
July Weather27°C (81°F)88 mm (3.5 inches)80%extreme
August Weather26°C (79°F)103 mm (4.0 inches)74%very high
September Weather23°C (74°F)128 mm (5.0 inches)75%very high
October Weather18°C (65°F)107 mm (4.2 inches)79%very high
November Weather10°C (51°F)87 mm (3.4 inches)87%moderate
December Weather8°C (46°F)119 mm (4.7 inches)87%moderate

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